Textile material and method of making same



Oct. 25, 1955 W. F. DACEY HAL Filed Jan. '7, 1954 3 Sheets-Sheet 1 IN VEN TOR` 1 BY A/EWMAM m AGENT Oct. 25, 1955 w. F. DAcEY ETAL 2,721,811

TEXTILE MATERIAL AND METHOD OF MAKING SAME Filed Jan. -'7, 1954 3 Sheets-Sheet 2 AGENT Oct. 25, 1955 w. F. DAcl-:Y ET AL 2,721,811

` TEXTILE MATERIAL AND METHOD OF' MAKING SAME Filed Jan. 7, 1954 3 Sheets-Sheet 3 E" wf nited States Patent TEXTILE MATERIAL AND METHOD OF MAKING SAME William F. Dacey, Waterbury, Conn., Robert A. Gregg, Passaic, N. J., and Newman W. Hess, Naugatuck, Conn., assigmors to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application January 7, 1954, Serial No. 402,746 18 Claims. (Cl. 117-65) This invention is concerned with an improved fabric and more particularly the invention relates to improved nylon fabric coated with a polyurethane elastomer, as Well as to a method of making such coated fabric.

This application is a continuation-in-part of our copending application Serial No. 373,849, and now abandoned, iiled August 12, 1953.

Although fabric made of nylon (synthetic linear polyamides) has a number of desirable qualities consequent to the great strength and resistance to chemical deterioration of the nylon, there has nevertheless existed the rather anomalous disadvantage of relatively poor wear resistance under certain circumstances in ordinary nylon fabrics. Thus, in spite of the superior physical properties of nylon in many respects, it is paradoxically found in practice that fabric uppers for sport shoes and the like made of nylon do not Wear as Well as the ordinary drill backed doubled cotton duck used for this purpose. Therefore, it has not been feasible up to the present time to take advantage of the strength and chemical inertness of nylon to make a superior shoe upper. Neither is this situation ameliorated by coating the nylon fabric according to any known process, because the prior coating processes either are not commercially practicable or because such coated nylon fabrics fail to perform Well under the conditions of use encountered in shoe uppers.

Accordingly, a principal object of the invention is to provide a coated nylon fabric having improved properties, especially from the standpoint of wear.

Another object is the provision of a method of coating nylon fabric that can be carried out efficiently and economicaliy.

Still a further object is to provide a coated nylon fabric that will not crease or tear readily and that is not brittle.

An additional object of the invention is the provision of a method of coating nylon fabric that is especially adapted for production of breathable fabrics.

it is still another object of the invention to provide an open mesh nylon fabric coated with a polyurethane elastomer that has been cured in situ on the nylon in such manner as to produce a smooth coating, free of surface irregularities and internal voids, and of good appearance.

The manner in which the invention accomplishes the foregoing objects, as Well as additional objects and advantages, will be made clear in the following detailed description, which is intended to be read with reference to the accompanying drawings, wherein:

Fig. 1 is a-iiow diagram representing one method of carrying out the invention;

Fig. 2 is a fragmentary plan view of a portion of nylon fabric prior to being treated in accordance with the invention;

Fig. 3 is a purely diagrammatic elevational view of an apparatus suitable for use in connection with the method outlined in Fig. l;

Fig. 4 is a transverse sectional view, taken along the line 4 4 of Fig. 2, of the fabric after it has been coated in accordance with the invention;

Fig. 5 is a diagrammatic side elevational View of an apparatus suitable for carrying out a modified method of coating fabric in accordance with the invention; and

Fig. 6 is a similar view of a portion of the apparatus at a later stage of operation.

The invention is based upon the discovery that successive treatments of nylon fabric with a polyesterdiisocyanate intermediate reaction product and a curing agent therefor are capable of producing in a rapid and eicient manner a nylon fabric that is coated with a rubbery polyurethane, and such fabric displays unprecedented resistance to wear under certain circumstances. Such coated nylon fabric provides a shoe upper material that is capable of far ontlasting the best fabrics previously employed for this purpose and, in fact, such coated nylon lfabric is apparently capable of lasting as long as the rubber portions of a shoe.

The nylon fabric employed in carrying out the invention may be any sort of conventional nylon fabric, and is typically a Woven nylon fabric. The invention finds particular application in the production of breathable fabrics, and to this end fabrics of an open or porous weave are preferred. Nylon fabrics woven of untwisted continuous multi-filament yarns are especially preferred because of the high tear resistance of such fabric. Such fabric is particularly preferable in the form of an open mesh Weave of the leno type.

According to the preferred practice of the invention, the coating material is formed in situ on the nylon fabric by the action of a diprimary diamine on an intermediate reaction product of a polyester with a diisocyanate. The polyester-diisocyanate intermediate reaction product is first prepared in a liquid state from a linear chain-extended polyester made from a glycol, for example, a mixture of ethylene and propylene glycols, and an aliphatic saturated dicarboxylic acid, for example, adipic acid, using an excess of glycol over the acid so that the resulting polyester contains terminal alcoholic hydroxyl groups. Usually such an amount of glycol is used as to give a polyester having a hydroxyl number of 20 to 120, and preferably 36 to 67, and a low acid value less than 2 and preferably less than 1. The molecular weight of the polyester preferably ranges from 1700 to 3000. This polyester is reacted With a diisocyanate, for example, naphthalene l,5diisocyanate or p,pdiphenylmethane diisocyanate, using a considerable molar excess, commonly from a 20% to a 250% and preferably from a 50% to a 100% molar excess, of the diisocyanate over that amount which would be required to react with all of the alcoholic hydroxyl groups furnished by the polyester. The reaction is frequently effected by heating a mixture of the polyester and the diisocyanate under anhydrous conditions at an elevated temperature, e. g., 70-150 C., to form a soluble, uncured, liquid material which is a linear polyurethane having terminal isocyanate groups.

The diisocyanates employed in preparing the liquid polyester-diisocyanate intermediate may be represented by the general formula OCN-R-NCQ where R is a divalent hydrocarbon radical, as in polymethylene diisocyanates such as ethylene diisocyanate, hexamethylene diisocyanate and tetramethylene diisocyanate, alkylene diisocyanates such as propylene-1,2-diisocyanate, cycloalkylene diisocyanates such as l,4-diisocyanatecyclo hexane, as Well as aromatic diisocyanates such as rnand p-phenylene diisocyanate, toluene diisocyanate, p,p'diphenyl diisocyanate and 1,5-naphthalene diisocyanate, in which category We include aliphatic-aromatic diisocyanates such as p,pdiphenylmethane diisocyanate and phenylethylene diisocyanate The invention contemplates application of such a polyester-diisocyanate intermediate containing unreacted isocyanate groups to the nylon fabric in any convenient manner, such as by spreading, brushing, dipping or spraying, using the polyester-diisocyanate as such, or using a solution of the polyester-diisocyanate intermediate in a suitable solvent, which is thereafter evaporated. The polyester-diisocyanate intermediate would ordinarily remain on the nylon fabric in an essentially fluent and tacky condition for impractically long periods of time, and in such condition the fabric would of course not be suitable for further processing or for fabrication into useful articles having the desired properties. However, if a diprimary diamine is associated with the polyester-diisocyanate intermediate on the fabric, such polyester-diisocyanate can be converted to a tack-free condition with surprising rapidity, providing very quickly a coated fabric that can be further processed and fabricated with ease. Either on standing or as a result of heating, the deposited polyester-diisocyanate, under the inuence of the diprimary diamine, is converted into what may be regarded as a substantially fully cured condition, in which the coating has the form of a polyurethane rubber of excellent physical properties, with the nylon firmly and integrally embedded therein.

The diprimary diamines suitable for this purpose may be represented by the general formula NHz-A-N-Ia, where A is a divalent organic radical in which the terminal atoms are carbon, and which is preferably devoid of groups reactive with diisocyanate, that is, the two primary amino groups are preferably the sole groups in the molecule that will react with the diisocyanate groups of the polyester-diisocyanate, to provide the desired curing action. In the preferred diprimary diamines employed in the invention the two primary amino groups are linked by a divalent hydrocarbon radical, and such radical may be aliphatic, cyclo-aliphatic, aromatic, or any combination thereof, as in hexamethylenediamine, l,4diamino cyclohexane, mor p-phenylenediamine, 4,4-diaminodiphenylmethane, p(betaaminoethyl) aniline, 4(beta aminoethyl) cyclohexylamine, p(4aminocyclohexyl) aniline. However, the connecting radical between the two essential primary amino groups need not be purely a hydrocarbon, but may contain other atoms in addition to carbon and hydrogen, as in 3,3diaminodipropyl ether, diaminodiphenyl ether and diamino-dibutyl sulfide.

The diprimary diamine, if it is a liquid at ordinary temperatures or at the temperature of application, may be applied to the fabric by spreading, brushing, dipping or spraying, or may be applied in any convenient manner from a solution, particularly if the diamine is not a liquid. The diamine may be applied to the fabric either before the polyester-diisocyanate liquid intermediate is applied, or the diamine may be applied subsequent to the application of the polyester-diisocyanate, or it may even be advantageous to apply the diamine both before and after applying the polyester-diisocyanate intermediate. It may also be advantageous in some cases to apply the polyesterdiisocyanate intermediate in more than one coat, either successively, or alternately with interspersed coatings of diamine. If desired, one of the materials, such as the polyester-diisocyanate, may be applied by one procedure, such as by dipping, while the other material, such as the diprimary diamine, may be applied by another procedure, such as by spraying. When applying the materials by spraying, relatively dilute solutions (e. g., by volume, i. e., l0 volumes of intermediate in 90 volumes of solvent) in any inert organic solvent are more suitable because of their lower viscosity, but more concentrated solutions (e. g., 50% by volume, i. e., 50 volumes of intermediate in 50 volumes of solvent) are more desirable when applying the materials by other techniques. Both sides of the fabric may be sprayed or otherwise treated in a single pass, or repeated passes on one or both sides may be employed to give alternate coatings of polyester-diisocyanate and diprimary diamine, or diprimary diamine and polyesterdiisocyanate, of the desired thickness. The thicker the layer of polyester-diisocyanate the more preferable it is to apply diprimary diamine both before and after the polyester-diisocyanate layer, in order to insure more thorough and homogeneous cure throughout the thickness of the polyester-diisocyanate layer by diffusion of the diamine into such layer from both sides.

The solvent employed as a vehicle for the polyesterdiisocyanate and the diprimary diamine is in no Way critical, and may be any inert, volatile, organic liquid in which these materials are soluble. Numerous different common organic solvents will readily dissolve the materials, and those skilled in the art will therefore have no difculty in selecting an appropriate solvent. Among the kinds of solvents suitable for use in the process may be mentioned hydrocarbons such as benzene, halogenated compounds such as methylene chloride, and ketones such as acetone. The preferred solvents, especially for the polyester-diisocyanate, are those which evaporate more slowly, i. e., those boiling above F., but the solvent should not be too high boiling, i. e., it should not have a boiling point in excess of, for example, 230 F., otherwise it will not be removed readily at the temperature of the curing treatment.

The action of the diamine on the polyester-diisocyanate intermediate on the nylon fabric is so rapid even at room temperature that within several minutes, and sometimes within as little as one minute after the application, the fabric is sufficiently tack free to be touched or passed over a roller without injury.

Reaction between the diamine and the polyester-diisocyanate intermediate is accelerated by elevated temperatures, and the treated fabric may be heated to a temperature of about 1GO-200 F. for a period of from about 1/2 to 30 minutes, whereupon the coating becomes sufficiently cured to enable the fabric to be wound upon itself into a roll without injury. After another 1/2-2 hours at such elevated temperature, the coating on the fabric has acquired a substantial degree of cure and it is sufficiently rm to permit extensive handling, and the fabric may be subjected, for example, to operations such as cutting, sewing and stamping, that might be necessary to convert the fabric into shoe uppers. At this stage the coating generally still has a rather soft plastic feel and it has not yet acquired the modulus that it is ultimately capable of achieving. Over a period of several more days of aging at room temperature a gradual further increase in the modulus of the coating slowly takes place.

The invention is particularly well adapted to making porous or breathable fabrics, but non-porous coated fabrics may also be produced by using more closely woven fabric and applying a coating that completely closes the pores. Such non-porous coated fabric is useful for making waterproof footwear, ponchos, tents, upholstery and the like.

Another method of producing the coated nylon of the invention involves treatment of nylon fabric with the polyester-diisocyanate intermediate reaction product, followed by treatment under carefully controlled conditions in a humid atmosphere, thereby effecting cure of the intermediate to a solid, non-tacky, rubbery state by the chemical action of water in the gaseous state. The rubbery polyurethane coating so produced has a pleasing, smooth surface appearance, and it is free from internal voids.

In order to obtain a smooth, regular surface on the coated nylon, as well as a coating that is free from internal voids and irregularities, it is essential that the polyester-diisocyanate be subjected in this method to the action of water or moisture in the vaporous or gaseous state, as distinguished from actual liquid or condensed water.

It is furthermore essential, in order especially toavoid internal voids in the coating, that the deposit of polyesterdiisocyanate which is subjected to the action of the moisture be extremely thin. The reason for this is that water reacts with the polyester-diisocyanate intermediate to produce carbon dioxide gas. Therefore, if there is a local high concentration of Water, as represented by condensed droplets of water on the surface of the deposit, excessive evolution of carbon dioxide will take place at such a locality, with consequent development of non-uniformities. Also, if the deposit of polyester-diisocyanate is too thick the carbon dioxide is unable to diffuse out of the coating sufiiciently rapidly and bubbles of the gas are developed within the film, or irregularities are produced as a result of extreme differences in the state of cure of the outer surface as compared to the inner layers, with consequent tendency to disruption and shrivelling of the film.

We have found that the foregoing difiiculties can be avoided by controlling the humidity of the treating atmosphere so that a relative humidity of 70 to 95%, and preferably 80 to 90%, prevails at a treatment temperature within the range of 100 to 400 F., and preferably 212 to 250 F., provided that the polyester-diisocyanate is deposited in a layer that is sufficiently thin to permit the carbon dioxide, evolved as a result of reaction between the water vapor and the polyester-diisocyanate, to diffuse out of the deposit substantially as rapidly asit is generated in order to avoid bubble formation, and the layer should also be sufficiently thin to permit substantial diffusion of the water vapor throughout the layer before the cure of the outer surface of the layer becomes advanced, in order to avoid shrivelling of the coating due to a marked differential in the state of cure between the surface of the film and the interior of the film. it is found in practice that the foregoing critical requirements are satisfied, under the conditions of humidity and temperature stated, when the amount of polyester-diisocyanate deposited in any individual coating step does not exceed about 70 grams per l() grams of the nylon, when using yarns or fabrics of the usual gauges. Films of this thickness or less are adequately cured to a sufficiently tack-free state to permit the nylon fabric to be rolled up without sticking within about to 60 minutes under the conditions stated. Thicker coatings are provided by repeated alternate treatments with the polyester-diisocyanate and water vapor.

in the step of treating the polyester-diisocyanate deposit on the nylon with moist heat we generally employ a temperature at least somewhat in excess of 212 F., say at least 220 F., and usually from 220 to 250 F., to forestall any condensation of water on the fabric, or on the surfaces of the treating chamber, from which the condensate might fall on the coated fabric, causing local non-uniformity of cure and gassing or discoloration. When using such preferred temperatures the desired condition of humidity is easily maintained by admitting live steam to a chamber in which the polyester-diisocyanate treated nylon is suspended or through which such nylon is conveyed ina continuous operation, with suitable provision for exhaust of solvent vapors. As long as the temperature of the treating chamber is maintained above the condensation point, deposition of water on the treated nylon is avoided.

In a preferred form of the invention the nylon fabric is treated one or two times with polyester-diisocyanate, with interspersed treatments with moist heat in the manner described, in such a way as to essentially saturate or impregnate the fabric without depositing substantial material externally of the fibers, and thereafter a third coating of polyester-diisocyanate is applied to provide a substantial external film over the fibers, whereupon the fabric is a third time subjected to the moist atmosphere treatment. It will generally be found that this third deposit of polyester-diisocyanate does not become substantially tack-free as readily as the previous deposits, possibly, at least in part, because of the comparatively reduced ratio of surface area to thickness of the third deposit. However, we have found that we can obviate difficulties from residual tackiness by winding the fabric up, after the humidity treatment, with a liner saturated with water. This is believed to have not only a lubri- Cating function which prevents sticking of the treated nylon but it is also believed to be conducive tocontinued' cure, and after an hour or so in such wound up condition the treated nylon is sufficiently tack-free to be handled further.

In the course of the foregoing processing we take precautions to maintain the open-mesh, breathable nature of the nylon fabric, and to this end we frequently provide means for blowing air or steam through the' freshly impregnated fabric to remove excess material from the interstices, and for the same reason we take care not to employ solutions too high in viscosity, particularly in the later coatings of a series of coating steps. Thus, although we typically employ a relatively concentrated solution, e. g., one containing 50% by volume of polyester-diisocyanate in the solvent, during the initial one or two coating steps wherein the bulk of the solutions is absorbed within the yarns themselves, we prefer to use a less concentrated solution, e. g., a 25% solution, in subsequent coating steps to avoid bridging, since the bulk of such subsequently applied solution remains on the outside of the yarns, which have previously been saturated by the earlier coatings.

It should be noted that in the method using moist heat as the curing medium, wherein the polyester-diisocyanate is typically deposited on the nylon fabric from a solution in an inert volatile organic solvent, such solvent is evaporated from the deposit in the presence of the moist heat applied as described. This has a beneficial effect on the character of the resulting film because the solvent tends to evaporate only very slowly in the humid atmosphere, thereby minimizing shrinkage or distortion effects. The fact that the initial deposit is subjected to the Water vapor while the deposit still contains a large proportion of solvent is also believed to facilitate diffusion of the Water vapor into the interior of the lm, particularly if the solvent employed is at least slightly solu` ble in water. To this end, it is preferred to employ solvents that have at least a slightly affinity for water, that is, solvents which are soluble in water to at least the extent of about 1%.

We typically carry out the step of coating the nylon with polyester-diisocyanate and the step of treating the thus-coated nylon with moist heat continuously in succession by conveying a long length of open mesh nylon fabric through a suitable coating or impregnating device in which the polyester-diisocyanate solution is applied, and thence through a long heated chamber into which live steam is introduced. The action of pulling a long length of open mesh nylon fabric through such an apparatus has a tendency to elongate the fabric lengthwise and correspondingly contract it widthwise, with consequent tendency for the pores of the fabric to become narrowed. We have found that we can avoid bridging of the coating from this cause by first applying a relatively small quantity of the polyester-diisocyanate, representing only a portion of the deposit ultimately desired in the finished fabric, and by then setting up or curing this limited deposit by the moist heat treatment with the result that the fabric becomes essenially stabilized or set against subsequent changes in the size or shape of the pores under the influence of tension applied to pull th'e nylon fabric through the apparatus during subsequent steps. Since the first deposit is comparatively light and easily cured, the length of the pass through the moist heat zone need not be excessive, compared tothe extremely long pass that would be required if the entire` desired quantity of polyester-diisocyanate were deposited in the' first instance. Such a comparatively short pass is easily effected without applying undue tension to the fabric, and hence distortion and narrowing of the pores is minimized, and thereafter, following the initial set in moist heat, the nylon fabric is comparatively immune to distortion and narrowing of the pores. Aside from the feature of setting the fabric against dimensional changes, application of the polyester-diisocyanate in two or more passes, rather than a single pass, has the advantage that in any single curing operation with hoist heat only a comparatively thin film of the deposit is being treated, so that there is less occasion for diculties due to non-uniform cure of the deposit, or development of gas bubbles therein. The moisture can more readily diffuse uniformly through a thin lm so that any tendency for greater cure at the outer surface of the film in comparison to the interior of the lm is minimized. Excessively rapid cure of the surface of the lm in comparison to the interior not only can give rise to differential shrinkage and wrinkling of the lm, but, once the surface has become advanced in cure it is more difficult for additional moisture to pass through to the interior of the lm, and it is more difcult for the evolved carbon dioxide to diffuse out. We have found it best to deposit in the rst coating step, as indicated previously, not more than about 70 grams of polyester-diisocyanate per 100 grams of open mesh nylon fabric of the usual gauges. After the moist heat treatment of this initial coating, we allow the treated nylon to stand at room temperature in a wound up condition for at least several hours, and preferably about l2 to 24 hours, during which time the cure advances further, to substantially set or stabilize the fabric. In subsequent steps we generally deposit even less than this, say 50 grams, or less, per 100 grams of nylon, because of the reduced ratio of surface area available for diffusion through the film.

The following examples will serve to illustrate the invention in more detail.

EXAMPLE 1 The essential steps of this example may be followed by reference to the flow diagram in Fig. l of the drawmg.

Referring to Fig. 3, a nylon fabric 10 was led from a roll 11 through a bath 12 composed of a 5% nonaqueous solution of 4,4-diaminodiphenylmethane in acetone. The nylon fabric was composed, as indicated in Fig. 2, of continuous untwisted multi-filament yarns 13 in an open mesh leno weave. The acetone was evaporated leaving a deposit of the 4,4diaminodiphenyl methane on the nylon fibers. The fabric bearing the 4,4- diaminodiphenylmethane was then led into a bath 14 composed of a 50% non-aqueous solution of a polyesterdiisocyanate intermediate in acetone. The polyester-diisocyanate intermediate was derived from a polyester made by heating the following mixture at 220-230" C.:

Moles Propylene glycol 11 Ethylene glycol 4.25 Adipic acid 11.25

The propylene glycol results in an alkyd of lower melting point and lower than viscosity. In the course of the preparation of the polyester the unreacted glycol was removed by vacuum distillation, and the extent of the distillation determined the molecular weight of the polyester, as calculated from the acid number and the hydroxyl number. The polyester used in this example had a molecular weight of about 1800, a hydroxyl number of about 60 and an acid number less than l. This alkyd was mixed at a temperature of 85 C. with an excess of p,p-diphenylmethane diisocyanate in the proportions of 80 parts of the polyester to 20 parts of the diisocyanate. A reaction occurred between the hydroxyl groups of the alkyd and the isocyanate groups to form a polyurethane intermediate characterized by the presence of unreacted isocyanate groups. This intermediate was a liquid and was soluble in the common organic solvents such as acetone.

After passing out the polyester-diisocyanate intermediate bath, the thus-impregnated fabric was passed between squeeze rolls 15, and thereafter the solvent was permitted to evaporate. The fabric was then passed across a jet 16 from which air issued at high velocity in order to remove any material that may have been deposited in the interstices of the fabric, thereby insuring a porous or breathable fabric. The fabric was then passed into a second bath 17 of 4,4diaminodiphenylmethane similar to the first bath, and thereafter the fabric was conveyed for a definite length of time in a free condition out of contact with any other surface while the initial set of the coating took place. During this time the diamine deposited on the surface of the fabric under the polyester-diisocyanate intermediate application as well as the diamine deposited on the outer surface of the polyesterdiisocyanate intermediate rapidly diffused into and acted upon the polyester-diisocyanate so that the coating was sufficiently tack-free within one minute to pass over a roll 18 and into a horizontal curing oven 19 without injury. The speed of the fabric throughout the successive impregnating operations was 2 yards per minute.

The thus-impregnated fabric required 3 minutes to traverse the oven, which was heated to a temperature of 180 F. Upon emerging from the oven, the material was sufficiently cured to be wound up upon itself in a roll 20. To advance the cure still further, the roll was placed in an oven at a temperature of 200 F. for an additional two hours. At the end of this time, the coating had a somewhat soft, plastic feel, but it was sufficiently cured to permit the fabric to be subjected to the operations necessary to make shoe uppers.

After aging for one day at room temperature the polyurethane rubber coated yarn had a breaking strength of 2400 p. s. i., and the breaking strength slowly increased with continued aging, reaching a value of 3100 p. s. i. after ve days.

The final fabric was characterized, as indicated in Fig. 4, by the fact that the nylon yarns 13 were surrounded by and rmly encased in a strong, flexible covering 21 of cured polyurethane elastomer, which served to bind the yarns together at the places where they crossed each other, thereby stabilizing the fabric and preventing the nylon yarns from rubbing and abrading on each other as the fabric was exed.

EXAMPLE 2 Referring to Fig. 5 of the drawings, an open mesh leno weave nylon fabric 25 of the kind described in Example l was led downwardly from the roll 26 between a pair of adjustable closely spaced driven coating rollers 27, containing a bank 28 consisting of a 50% by volume non-aqueous solution of polyester-diisocyanate intermediate of the kind specified in Example l in methyl isobutyl ketone. The solution was supplied to the bank from a conveniently located storage tank 29.

Upon passing through the rolls 27, a deposit or film 30 of polyester-diisocyanate intermediate solution was applied on and in the nylon fabric 25, and the fabric was thereafter passed horizontally into a long chamber or oven 31, provided in its lower portion with steam heating pipes 32 which maintained the atmosphere in the oven at a temperature of 220-230 F. Near the place where the fabric entered the oven, a jet 33 of steam was directed upwardly through the fabric to blow out any coating material that might bridge the pores of the fabric. Further jets 34 spaced throughout the length of the oven located near the fabrics served to inject suicient live steam into the oven to maintain the relative humidity at about Exhaust ducts 35 leading from the upper portion of the oven toward each end thereof served for removal of solvent vapors.

The fabric was conveyed through the oven at a speed of two yards per minute under thev influence of spaced driven supporting rollers 36 located at intervals throughout the oven, as well as a driven external wind-up roll 37 located just outside the far end of the oven. After leaving the coating rollers the fabric was unsupported until it extended about 20 feet into the oven, and therefore the coating had about three minutes exposure in the oven before touching the first supporting roller 36. This three minutes was sufficient, under the conditions described, to remove suflicient solvent from the coating, and to impart at least an initial cure to the coating, to avoid smearing or sticking of the coating on the supporting rollers. The fabric passed through the length of the oven in ten minutes, and when it emerged it was substantially non-tacky and cured sufliciently to be wound up on itself without sticking. In this operation 61 grams of polyester-diisocyanate were deposited on each 100 grams of fabric (equivalent to 100 grams of polyesterdiisocyanate per square yard of fabric). To more completely set the coating on the nylon, and thereby prevent further pulling down during subsequent processing, the coated nylon wound up on the roll 36 was permitted to stand at least l2 hours at room temperature, and after this time the coating was sufficiently cured to stabilize the fabric.

The coated fabric was thereafter once again passed through the coating rollers 27 and the oven 31 in the same manner, providing an additional deposit of 46 grams of polyester-diisocyanateper 100 grams of nylon (equivalent to 75 grams of polyester-diisocyanate per square yard of fabric).

The same procedure was repeated a third time, except that a 25% by volume solution of polyester-diisocyanate was used (25 volumes of polyester-diisocyanate in 75 volumes of methyl isobutyl ketone). This resulted in a deposit of 16 additional grams of polyester-diisocyanate per 100 grams of nylon fabric (25 grams of polyesterdiisocyanate per square yard) making a total deposit in the three coating steps of 122 grams per 100 grams of nylon (200 grams of polyester-diisocyanate per square yard). At the conclusion of this third stage of treatment the fabric upon emerging from the oven was wound up with a cloth liner 38 saturated with water, as indicated in Fig. 6, because the last coating of polyester-diisocyanate did not set completely tack-free in the oven 31, owing to the reduced ratio of surface area of the deposit, with consequent reduction in opportunity for moisture to diffuse into the coating. After about one hour in the Wet liner 38, the coating had a somewhat soft, plastic feel, but it was sufficiently cured to permit the fabric to be subjected to the operations necessary to make shoe uppers. However, optimum physical properties were not obtained until after about 7 days had passed. The cured rubbery polyurethane coating obtained in this example was more smooth, glossy, and pleasing in appearance than that obtained in Example l.

From the foregoing examples it will be apparent that the invention provides a rubbery polyurethane coating formed in situ on a nylon fabric by a method that is adapted to continuous and rapid production. Because the polyester-diisocyanate is applied to the nylon fabric at an intermediate stage in a liquid form, the impregnation of the nylon can be carried out easily and uniformly, and without expensive equipment. By subjecting the polyester-diisocyanate on the fabric to the action of a diprirnary diamine or moist heat, the polyester-diisocyanate intermediate is rapidly converted from its fluent and tacky state into a comparatively rigid and non-tacky condition in which it can be handled without injury. The resulting polyurethane rubber formed in situ onv the nylon constitutes an integral protective coating for the nylon that makes the vfabric capable of superior performance under diflicult conditions of use, such as are encountered in fabric shoe uppers.

In order to demonstrate the superior properties of the present polyurethane rubber coated nylon, tennis shoes were constructed with uppers made of the coated nylon fabric. The shoes were worn by an athletic team over an extended period of time, and were thereby demonstrated to have better wearing characteristics than shoes made with the best previously known material for uppers, namely, drill backed cotton army duck. These results were particularly surprising in view of the fact that nylon fabric is ordinarily definitely inferior to drill backed duck. In this test the athletic team also reported a definite comfort advantage for the present fabric upper because of the open mesh nature of the fabric, with consequent unusual degree of breathableness and coolness on the foot.

It should be pointed out that such open mesh nature and consequent breathableness could not be obtained with uncoated nylon or other fabric, because open mesh fabrics are too unstable for practical use as a shoe upper. Even in the leno Weave, the fill fibers in the uncoated fabric slide readily on each other.

It should also be pointed out that the results of the present invention cannot be obtained in practice by coating the nylon with other materials. Thus, if the nylon is coated with ordinary rubber, the present results are not obtained because the fabric is not stable and wear resistant like the polyurethane coated fabric of the invention. Similarly, if the nylon fabric is coated with vinyl resin, or other plastics, or mixtures of rubber with resin, the resulting fabric does not have the properties of the polyurethane coated nylon of the invention. A particular disadvantage of such other coated fabrics is evidenced by their inferior resistance to failure from flex cracking. Such materials are susceptible of forming creases at certain local areas where they are severely flexed, and such creases establish a slight weakness, so that the fabric tends to continue t0 flex again and again at the locality of the original crease, with resulting early failure at this point. This is a well known characteristic of ordinary fabrics, and it is manifested by the fact that such articles as fabric shoe uppers generally wear out rst at the points of greatest flexing, rather than at the areas of greatest abrasion, as might at first be supposed. In contrast to the behavior to other fabrics, the polyurethane coated nylon of the invention will not form creases readily where it is subjected to severe flexing, and therefore no points of rapid wear are established in the fabric. This is believed to be a principal reason why the present fabric wears better than other fabrics.

While it is not intended to limit the invention to any particular theory of operation, it appears possible that the superior characteristics of the present fabric are due to a strong physical and/ or chemical affinity between the nylon and the polyurethane coating formed in situ, so that the two materials together behave essentially as an integral unit, instead of as dissimilar materials, as seems to be the case when nylon is coated with other materials. When nylon coated with other materials is flexed severely a definite whitening is generally noted along the line of flex, indicating that the structure is essentially non-homogeneous, Whereas with nylon coated with polyurethane formed in situ as described, this leffect is not observed, indicating that the polyurethane and the nylon behave essentially as a homogeneous unit even when subjected to severe bending strains. The unusually integral union between the polyurethane coating and the nylon is apparently a consequence of the fact that the cured polyurethane is formed in situ on the nylon by separate application of the polyester-diisocyanate intermediate reaction product in a liqquid, normally tacky, uncured condition, followed by treatment with a diprimary diamine or moist heat to convert the polyester-diisocyanate intermediate from such an uncured tacky state into a solid, non-tacky cured condition, all as described in detail previously.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. A breathable open mesh fabric comprised of nylon coated with a polyurethane elastomer formed in situ on the nylon by reaction of (A) a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, with (B) a curing agent for said polyester-diisocyanate intermediate, whereby said polyester-diisocyanate intermediate is converted on the nylon into a solid non-tacky cured condition with the nylon firmly embedded therein.

2. A nylon fabric coated with a polyurethane elastomer formed in situ on the nylon by reaction thereon of (A) a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, with (B) a diprimary diamine, whereby said polyesterdiisocyanate intermediate is converted on the nylon into a solid non-tacky cured condition with the nylon firmly embedded therein.

3. A breathable open mesh fabric comprised of nylon coated with a polyurethane elastomer formed in situ on the nylon by reaction of (A) a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, with (B) a diprimary diamine, whereby said polyester-diisocyanate intermediate is converted on the nylon into a solid non-tacky cured condition with the nylon firmly embedded therein.

4. A breathable material characterized by improved wear resistance comprising untwistcd nylon yarns in a leno weave coated with a polyurethane elastomer formed in situ on the nylon by reaction of (A) a normally tacky liquid p'olyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups with (B) a diprimary diamine, whereby said polyester-diisocyanate intermediate is converted on the nylon into a solid, nontacky cured condition with the nylon firmly embedded therein.

5. A nylon fabric coated with a polyurethane elastomer formed in situ on the nylon by reaction of (A) a normally tacky liquid intermediate reaction product of (l) a polyester having a hydroxyl number of from 20 to 120 and an acid value less than 2, with (2) a 20% to a 250% molar excess of a diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, and (B) a diprimary diamine, whereby said intermediate is converted on the nylon into a solid non-tacky cured condition with the nylon firmly embedded therein.

6. A nylon fabric coated with a polyurethane elastomer formed in situ on the nylon by reaction of (A) a normally tacky liquid intermediate reaction product of (1) a glycoladipic acid polyester having a hydroxyl number of from 36 to 67, an acid value less than 1, and a molecular weight of from 1700 to 3000, with (2) a 50% to 100% molar excess of an aromatic diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, and (B) a diprimary diamine in which the amino groups are linked to terminal carbon atoms of a divalent hydrocarbon radical, whereby said intermediate is converted on the nylon into a solid non-tacky cured condition with the nylon firmly embedded therein.

7. A nylon fabric coated with a polyurethane elastomer formed in situ on the nylon by reaction of (A) a normally tacky liquid intermediate reaction product of (l) an ethylene and propylene glycol-adipic acid polyester having a hydroxyl number of from 36 to 67, an acid value less than l, and a molecular weight of from 1700 to 3000, with (2) a 50% to 100% molar excess of p,pdipheny1 methane diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, and (B) p,pdi aminodiphenylrnethane, whereby said intermediate is converted on the nylon into a solid non-tacky cured condition with the nylon firmly embedded therein.

8. A method of coating nylon comprising in combination the steps of applying to the nylon in an uncured condition a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, and subsequently curing the said polyester-diisocyanate intermediate on the nylon, whereby the said polyester-diisocyanate intermediate is converted on the nylon into a solid, non-tacky cured condition with the nylon firmly embedded therein.

9. A method of coating nylon comprising in combination the steps of separately applying to the nylon (A) a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups and (B) a diprimary diamine, and subsequently heating the thus-treated nylon to bring about reaction between the polyester-diisocyanate intermediate and the diamine on the nylon, whereby the said polyester-diisocyanate intermediate is converted on the nylon into a solid, non-tacky cured condition with the nylon firmly embedded therein.

10. A method of making a coated nylon fabric comprising in combination the steps of separately applying to the nylon (A) a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups and (B) a diprimary diamine, supporting the thus-treated fabric in a free condition out of contact with other objects until said polyester-diisocyanate intermediate is converted into a solid, non-tacky condition, and heating the assembly to substantially advance cure of the said polyester-diisocyanate by the said diamine to produce on the nylon a rubbery polyurethane elastomer with the nylon iirmly embedded therein.

11. A method of making a breathable coated nylon fabric comprising in combination the steps of providing an open mesh woven nylon fabric, separately applying to the nylon fabric (A) a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups and (B) a diprimary diamine, blowing a jet of air through said fabric to remove any of the said materials from the interstices of the fabric, supporting the thus-treated nylon fabric in a free condition out of contact with other objects until said diamine has converted said polyester-diisocyanate intermediate on the nylon into a solid, non-tacky condition, and heating the assembly to substantially advance the cure of the polyester-diisocyanate intermediate by the diamine to form on the nylon a rubbery polyurethane elastomer with the nylon firmly embedded therein.

12. A method of coating nylon comprising in combination the steps of separately applying to the nylon (A) a solution of a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, and (B) a solution of a diprimary diamine, evaporating the solvent from said solution, and heating the thus-treated nylon to bring about reaction between the polyester-diisocyanate intermediate and the diprimary diamine on the nylon, whereby the said polyester-diisocyanate intermediate is converted on the nylon into a solid, non-tacky cured condition with the nylon firmly embedded therein.

13. A method of coating nylon with a rubbery polyurethane comprising in combination the steps of separately impregnating the nylon with non-aqueous solutions of (A) a normally tacky liquid intermediate reaction product of (1) a polyester having a hydroxyl number of from 20 to and an acid value less than 2, with (2) a 20% to a 250% molar excess of a diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, and (B) a diprimary diamine, evaporating the solvent from the impregnated nylon, and heating the thus-treated nylon, whereby the said intermediate is converted on the nylon into a solid, non-tacky cured condition with the nylon firmly embedded therein.

14. A method of coating nylon with a polyurethane elastomer comprising in combination the steps of rst applying to the nylon a solution of a diprimary diamine, evaporating the solvent therefrom, thereafter applying a solution of a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, evaporating the solvent therefrom, and

subsequently applying a second solution of a diprimary diamine and evaporating the solvent, and thereafter heating the thus-treated nylon to bring about reaction between the polyester-diisocyanate intermediate and the diprimary diamine on the nylon, whereby the said polyester-diisocyanate intermediate is converted on the nylon into a solid, non-tacky cured condition with the nylon firmly embedded therein.

15. A method of applying a rubbery polyurethane coating to a nylon fabric comprising in combination the steps of contacting the nylon fabric with separate solutions of (A) a normally tacky liquid reaction product of (1) a glycol-adipic acid polyester having a hydroxyl number of from 36 to 67, an acid value less than 1 and a molecular weight of from 1700 to 3000, with (2) a 50% to 100% molar excess of an aromatic diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, and (B) a diprimary diamine in which the amino groups are linked to terminal carbon atoms of a divalent hydrocarbon radical, evaporating the solvent from said solutions on the fabric, and heating the thus-treated fabric, whereby .said intermediate is converted on the nylon fabric into a solid non-tacky cured condition with the nylon fabric firmly embedded therein.

16. A method of coating a nylon fabric with a polyurethane elastomer comprising in combination the steps of applying to the nylon fabric separate solutions of (A) a normally tacky liquid intermediate reaction product of (1) an ethylene and propylene glycol-adipic acid polyester having a hydroxyl number of from 36 to 67, an acid value less than l, and a molecular weight of from 1700 to 3000, with (2) a 50% to 100% molar excess of p,pdiphenyl methane diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, and (B) p,pdiaminodiphenylmethane, removing the solvent from the thus-treated nylon fabric, and thereafter heating the thustreated nylon fabric to convert said intermediate on the nylon fabric into a solid non-tacky cured condition with the nylon fabric firmly embedded therein.

17. A method of making a breathable coated nylon fabric comprising in combination the steps of providing an open mesh woven nylon fabric, applying to the nylon fabric a normally tacky liquid polyester-diisocyanate intermediate reaction product containing unreacted isocyanate groups, and thereafter subjecting the fabric to an atmosphere having a temperature of at least 212 F. and a relative humidity within the range of to 95% until said polyester-diisocyanate intermediate has been converted on the nylon into a solid, cured condition, whereby there is formed on the nylon a rubbery polyurethane elastomer with the nylon rmly embedded therein.

18. A method of making a coated nylon fabric comprising in combination the steps of applying to the nylon a solution in a volatile inert organic solvent having a boiling point within the range of from to 230 F. and a solubility in water of at least 1%, of a normally tacky liquid intermediate reaction product of (l) a polyester having a hydroxyl number of from 20 to 120 and an acid value less than 2, with (2) a 20% to 250% molar excess of a diisocyanate, said intermediate reaction product containing unreacted isocyanate groups, the amount of said polyester-diisocyanate intermediate deposited on the nylon being not greater than 70 grams per 100 grams of nylon, passing the nylon fabric bearing the said solution into a chamber containing an atmosphere maintained at a temperature within the range of from 212 to 250 F. and at a relative humidity of S0 to 90% to simultaneously evaporate the said solvent from the coated nylon and cure the polyster-diisocyanate under the influence of such moist heat, whereby the said polyester-diisocyanate intermediate is converted on the nylon into a solid, rubbery polyurethane with the nylon rmly embedded therein, storing the thus-treated fabric for about 12 hours to stabilize it dimensionally, repeating said application of said solution and moist heat until there is formed on the fabric a deposit of said polyurethane rubber of definite desiredv thickness and at the conclusion of a final such treatment with moist heat winding up the fabric in a cloth liner saturated with water, and maintaining the fabric in such wound condition for one hour to advance the cure of the polyurethane rubber to the stage where the fabric can be further handled without injury to the coating.

References Cited in the file of this patent UNITED STATES PATENTS 2,370,562 Meunier Feb. 27, 1945 2,491,454 Nute Dec. 13, 1949 2,625,531 Seeger Jan. 13, 1953 2,650,212 Windemuth Aug. 25, 1953 2,657,151 Gensel et' al Oct. 27, 1953 

17. A METHOD OF MAKING A BREATHABLE COATED NYLON FABRIC COMPRISING IN COMBINATION THE STEPS OF PROVIDING AN OPEN MESH WOVEN NYLON FABRIC, APPLYING TO THE NYLON FABRIC A NORMALLY TACKY LIQUID POLYESTER-DIISOCYANATE INTERMEDIATE REACTION PRODUCT CONTAINING UNREACTED ISOCYANATE GROUPS, AND THEREAFTER SUBJECTING THE FABRIC TO AN ATMOSPHERE HAVING A TEMPERATURE OF AT LEAST 212* F. AND A RELATIVE HUMIDITY WITHIN THE RANGE OF 70 TO 95% UNTIL SAID POLYESTER-DIIOCYANATE INTERMEDIATE HAS BEEN CONVERTED ON THE NYLON INTO A SOLID, CURED CONDITION, WHEREBY TTHERE IS FORMED ON THE NYLON A RUBBERY POLYURETHANE ELASTOMER WITH THE NYLON FIRMLY EMBEDDED THEREIN. 